Thermoplastic resins are important materials that are indispensable in the modern world because they not only are light weight and easy to process but also have excellent properties in that, for example, their base materials can be designed in accordance with the intended use. In addition, thermoplastic resins have excellent electrical insulation properties; therefore, they are often utilized in the components and the like of electrical appliances. However, there is also a problem that thermoplastic resins are easily electrically charged by friction or the like because of excessively high insulation performance.
An electrically charged thermoplastic resin attracts dust and dirt in the surroundings and thus causes a problem of deteriorating the outer appearance of its molded article. Further, among electronic products, for example, in precision instruments such as computers, electric charge may interfere with normal operation of a circuit. Moreover, there are also problems that are caused by an electric shock. An electric shock to a person from a resin not only causes discomfort but also potentially induces accidental explosion in the presence of flammable gas or dust.
In order to resolve these problems, synthetic resins are conventionally subjected to an antistatic treatment. The most common antistatic treatment method is an addition of an antistatic agent to a synthetic resin of interest. Examples of the antistatic agent include coating-type antistatic agents that are coated on the surface of a resin molded article and kneading-type antistatic agents that are added when a resin is molded; however, the coating-type antistatic agents have poor persistence, and coating of a large amount of such an organic substance on a surface leads to a problem that objects coming into contact with the surface are contaminated.
From these perspectives, conventionally, kneading-type antistatic agents have mainly been examined and, for example, the use of polyether ester amide has been proposed for the purpose of imparting antistatic properties to polyolefin-based resins (Patent Documents 1 and 2). Furthermore, a block polymer having a structure in which a polyolefin block and a hydrophilic polymer block are repeatedly and alternately bound with each other has been proposed (Patent Document 3).